One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(10,11)(13,21)(15,17)(20,24)(25,26,31,34)(27,35,36,28)(29,32,30,33)(37,40,38,39)(1,2,4,6)(3,5,8,7)(9,10,14,11)(12,15,19,17)(13,16,21,18)(20,22,24,23)(27,36)(28,35)(37,38)(39,40)(1,2)(3,5)(4,6)(7,8)(12,19)(15,17)(20,24)(22,23)(25,27)(26,28)(29,37)(30,38)(31,36)(32,39)(33,40)(34,35) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,14,10)(12,17,19,15)(13,18,21,16)(20,23,24,22)(25,28)(26,27)(29,39)(30,40)(31,35)(32,37)(33,38)(34,36)(9,12,14,19)(10,15,11,17)(13,20,21,24)(16,22,18,23)(25,29,31,30)(26,32,34,33)(27,37,36,38)(28,39,35,40)(9,13)(10,16)(11,18)(12,20)(14,21)(15,22)(17,23)(19,24)(25,30,31,29)(26,33,34,32)(27,38,36,37)(28,40,35,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.